The present disclosure relates to a torquemeter for monitoring torque transferred between rotating shafts. In particular, the torquemeter of the present disclosure provides a dual load path to assure that a desired quantity of torque may be transmitted through the torquemeter. Kop-Flex has successfully sold torquemeters constructed in accordance with U.S. Pat. No. 5,969,269 entitled Flexible Coupling with Torque Measuring and Detecting Device, which is herein incorporated by reference. Another commonly owned torquemeter is patented under U.S. Pat. No. 5,450,761 which is also herein incorporated by reference. The existing Kop-Flex torquemeters were typically used in torque transfer applications that had a low threat of high transient torques. More recently, torquemeters are being installed and/or requested for use in a wider variety of applications. Many of the new applications subject the torquemeter to relatively large transient torques.
The new application criterion creates a design challenge. To provide a torquemeter with a desired accuracy at a nominal torque level, the torquemeter must exhibit a measurable amount of torsional twist. As such, the torquemeter must be relatively torsionally soft. A contradicting requirement arises with the need to transmit large transient torques. If a large transient torque were transmitted through a torquemeter designed for a much lower nominal torque, the components may become overstressed and may no longer transmit torque. On the other hand, if the torquemeter is designed to transmit the full maximum transient torque, a measurable amount of torsional twist will not occur and the torque measurement will be at best inaccurate.
Furthermore, new applications require that some member other than the torquemeter be the weakest link in the torque transfer driveline. For example, some turbo-machinery customers require that a flexible element be the weakest link in the driveline. Failing flexible element components may be more easily contained in the unlikely event of a catastrophic failure. As such, the torquemeter must be rated to transfer a quantity of torque at least greater than that of the weakest link in the driveline. Furthermore, recently designed turbo-machinery operates at higher power and increased rotational speeds as compared to earlier designs. As such, torquemeters that are limited to operation on applications less than 8000 rpm may not meet the needs of the customers.
Accordingly, to address the changes in turbo-machinery requirements and applications for torquemeters, it may be desirable to provide an improved torquemeter.